Patent Application WO 94/05995 discloses an apparatus for the dewatering and/or embedding of preferably frozen specimens. The apparatus encompasses a Dewar vessel filled with liquid nitrogen and a metallic element, anchored at the base of the Dewar vessel, that is made of a material having good thermal conductivity. The metallic element possesses at its upper end, in the Dewar neck attachment region, a cover having a metallic cooling surface. Provided in the Dewar neck is a substitution (PLT) container in which the transfer of liquids for low-temperature substitution is performed manually.
The brochure for the Leica EM AFS discloses a unit according to the existing art. A Dewar vessel is filled with liquid nitrogen, the Dewar neck comprising a chamber or a container that can be brought to a specific temperature. The temperature range extends from −140° C. to +65° C. The desired temperature is set via a control loop and built-in heating elements. Here as well, liquid exchange must be accomplished manually.
German Utility Model DE 91 04 344.1 discloses a cooling device for specimen preparation for an electron microscope. The cooling device encompasses a holding insert that is subdivided into at least two segments. Both segments are equipped with orifices, of which the orifices in one segment serve to retain a container for the specimens to be freeze-dried. Reservoir vessels having reagents are retained in the orifices of the other segment. The specimens and the reagents are thereby cooled to the required working temperature. An automatic transfer of the reagents from one region of the container into the next is not disclosed.